1. Field of the Invention
The present invention relates to a method of fabricating a light-guide plate, and more particularly, to a method of fabricating a light-guide plate for a liquid crystal display module.
2. Description of the Related Art
In general, liquid crystal display (LCD) devices display images using an external light source. FIG. 1 is a schematic cross sectional view of a liquid crystal display module according to the related art. In FIG. 1, a liquid crystal display module includes a main support 2, a backlight unit and a liquid crystal display panel 10 stacked inside the main support 2, a bottom cover 14 enclosing bottom and side surfaces of the main support 2, and a case top 16 for enclosing edges of the liquid crystal display panel 10 and the bottom cover 14.
The main support 2 is a molded part and side surface of an inner wall of the main support 2 is formed to have a step portion. In addition, a backlight unit is installed on the inner bottom portion of the main support 2, and the liquid crystal display panel 10 is mounted above the backlight unit.
The liquid crystal display panel 10 includes a lower substrate 10b upon which switching devices, such as thin film transistors TFT are installed, an upper substrate 10a upon which color filters are installed, and a liquid crystal material injected into a space between the upper substrate 10a and the lower substrate 10b. Polarizing plates 22 and 24 are installed above and below the liquid crystal display panel 10, wherein the lower polarizing plate 22 polarizes light coming from the back light unit and guides the polarized light to the liquid crystal display panel 10. The upper polarizing plate 24 polarizes the polarized light coming through the liquid crystal display panel 10 and transmits the doubly-polarized light.
The bottom cover 14 is installed to enclose the bottom and side surfaces of the main support 2. In addition, the case top 16 is installed to enclose the upper and side portions of the main support 2 to affix the main support 2 and the liquid crystal display panel 10 together.
The backlight unit includes a lamp housing 18 accommodating a light source 20, a light-guide plate 6 for transforming the incident light emitted from the light source 20 into planar light, optical sheets 12 attached onto the light-guide plate 6 for increasing efficiency of the light incident to the liquid crystal display panel 10, and a reflection plate attached onto a rear surface of the light-guide plate 6 for reflecting the light transmitted from the back of the light-guide plate 6 to the liquid crystal display panel 10.
The light source 20 supplies amounts of light to the light-guide plate 6 in response to an extremely supplied power. Accordingly, the light radiated to the opposite direction of the light-guide plate 6 is reflected toward the light-guide plate 6 by the lamp housing 18, and the reflection plate 4 reflects the light incident to the lower part of the light-guide plate 6. Thus, the reflection plate 4 guides the incident light from the light-guide plate 6 toward the liquid crystal display panel 10.
The optical sheets 12 include upper and lower diffusion sheets and upper and lower prism sheets. The optical sheets scatter the light incident from the light-guide plate 6 to distribute the lights evenly over an entire surface of the light-guide plate 6. In addition, the optical sheets 12 increase surface brightness by refracting and collecting the scattered light, thereby widen a viewing angle by diffusing the light.
FIG. 2 is a cross sectional view of the light-guide plate of FIG. 1 according to the related art. In FIG. 2, a plurality of protrusions 30 are formed on a rear surface of the light-guide plate 6 to reflect the incident light and to uniformly distribute the light and guide the light toward the liquid crystal display panel 10.
FIG. 3 is a cross sectional view of a mold frame used to mold the light-guide plate of FIG. 2 according to the related art. In FIG. 3, a plurality of grooves 36 are formed within designated intervals on a lower mold frame 32 in order to create the plurality protrusions 30. Then, an upper mold frame 34 is provided to have an inclined inner surface. Next, a light-guide plate forming material, such as polymethyl methacrylate (PMMA), is inserted between the upper and lower mold frames 34 and 32, and the light-guide plate 6 is formed, as shown in FIG. 2.
However, during the process for forming the light-guide plate 6, since a plurality of grooves 36 are directly formed on the lower plate, it is difficult for the intervals between the protrusions 30 to be less than or equal to 10 μm. Similarly, the interval between the protrusions 30 is formed to be greater than or equal to 10 μm. Accordingly, the protrusions 30, where the interval between the protrusions is greater than or equal to 10 μm, are limited in the amount of light reflected therefrom, and result in lowering the uniformity of light and making it be difficult to implement high light brightness.